Recovery of the visual acuity in a family with Reis-Bückler dystrophy.

BACKGROUND: The hereditary Reis-Bückler dystrophy is one of the anterior localised corneal dystrophies with superficial reticulated opacities, sometimes in combination with recurrent attacks of corneal erosion. Phototherapeutic keratectomy (PTK) is now the first method to consider for managing this disease when intervention is required. METHODS: We treated six eyes of four related patients with Reis-Bückler dystrophy, who had a demonstrable reduction in visual acuity due to corneal opacities within their virgin corneas (three eyes), penetrating (one eye) or lamellar (two eyes) grafts. We present the results of change in visual acuity and best corrected spherical spectacle and contact lens refraction at 1 year following surgery. In one case, we had to fit a rigid contact lens to correct the hyperopic shift which caused anisometropia. RESULTS: The mean spherical refractive change 1 year after PTK surgery was 0.33+/-S.D., 1.8D. A hyperopic shift was observed in four eyes. Visual acuity remained stable in all patients 1 year after surgery. The central corneal area remained clear, and mean best spectacle corrected visual acuity improved from +0.8 logMAR before PTK to +0.15 logMAR after 1 year. There was no significant change (P>0.8) between the mean 1 year best spectacle corrected visual acuity (+0.125 log MAR +/- S.D. 0.15) and the best contact lens corrected visual acuity (+0.108 log MAR +/- S.D. 0.16). After fitting a contact lens in one patient to correct anisometropia, the hyperopic shift did not change significantly during 12 months of follow-up. It was not necessary to adjust the lens parameters. One patient required cataract surgery. CONCLUSION: PTK corneal surgery is the treatment of first choice when intervention is required in patients with Reis-Bückler dystrophy because it is safe and much less invasive than lamellar or penetrating keratoplasty. Contact lens fitting following PTK has not changed corneal shape.     

Development and application of new composite materials as EDM electrodes manufactured via selective laser sintering

The cost of a part manufactured by electrical dischargeEDM machining (EDM) is mainly determined by electrode cost. The production of electrodes by conventional machining processes is complex, time consuming, and can account for over 50 % of the total EDM process costs. The emerging additive manufacturing (AM) technologies provide the possibility of direct fabrication of EDM electrodes. Selective laser sintering (SLS) is an alternative AM technique because it has the possibility to directly produce functional components, reducing the tool-room lead time and total EDM costs. The main difficulty of manufacturing an EDM electrode using SLS is the selection of an appropriate material, once both processes require different material properties. The current work focused on the investigation of appropriate materials that fulfill EDM and SLS process demands. Three new metal-matrix materials composed of Mo–CuNi, TiB₂–CuNi, and ZrB₂–CuNi were developed and characterized. Electrodes under adequate SLS conditions were manufactured through a systematic methodology. EDM experiments using different discharge energies were carried out, and the performance evaluated in terms of material removal rate and volumetric relative wear. The results showed that the powder systems composed of Mo–CuNi, TiB₂–CuNi, and ZrB₂–CuNi revealed to be successfully processed by SLS, and the EDM experiments demonstrated that the new composite electrodes are promising materials. The work also suggests important topics for future research work on this field.     

An explicit finite element model to study the influence of rake angle and friction during orthogonal metal cutting

A fundamental understanding of the tribology aspects of machining processes is essential for increasing the dimensional accuracy and surface integrity of finished products. To this end, the present investigation simulates an orthogonal metal cutting using an explicit finite element code, LS-DYNA. In the simulations, a rigid cutting tool of variable rake angle was moved at different velocities against an aluminum workpiece. A damage material model was utilized for the workpiece to capture the chip separation behavior and the simultaneous breakage of the chip into multiple fragments. The friction factor at the cutting tool–workpiece interface was varied through a contact model to predict cutting forces and dynamic chip formation. Overall, the results showed that the explicit finite element is a powerful tool for simulating metal cutting and discontinuous chip formation. The separation of the chip from the workpiece was accurately predicted. Numerical results found that rake angle and friction factor have a significantly influence on the discontinuous chip formation process, chip morphology, chip size, and cutting forces when compared to the cutting velocity during metal cutting. The model was validated against the experimental and numerical results obtained in the literature, and a good agreement with the current numerical results was found.     

Development and application of copper–nickel zirconium diboride as EDM electrodes manufactured by selective laser sintering

The production of electrical discharge machining (EDM) electrodes by conventional machining processes can account for over 50 % of the total EDM process costs. The emerging additive manufacturing (AM) technologies provide the possibility of direct fabrication of EDM electrodes. Selective laser sintering (SLS) is an alternative AM technique because it has the possibility to reduce the tool-room lead time and total EDM costs. The main difficulty of manufacturing an EDM electrode using SLS is the selection of an appropriate material. This work investigated the direct production of EDM electrodes by means of the SLS using a newly developed non-conventional metal–matrix composite material composed of a metallic matrix (CuNi) and an advanced ceramic (ZrB₂). The influence of important SLS parameters and material content on the densification behavior and porosity of the electrodes was investigated. EDM experiments were conducted to observe the electrodes behavior and performance. It was found that the ZrB₂-CuNi electrodes could be successfully manufactured by SLS. Interlayer bonding and porosity are directly influenced by the layer thickness. Smaller layer thicknesses improved bonding between layers and decreased the porosity of the parts. The laser scan speed has a significant effect on the densification behavior. The scan line spacing affects the pore structure by means of overlapping. The surface morphology of the samples was not affected by varying the scan line spacing. The ZrB₂-CuNi electrodes presented a much superior performance than SLS copper powder electrodes, but inferior to solid copper electrodes.     

卫生用品非织造布的来来--从迫切需要到可持续发展

0引言 近一两年我一直在思考影响非织造布行业未来发展的重要问题:是什么因素能使非织造布行业获得成功?非织造布行业的未来将是什么样的?是什么条件为非织造布行业提供着增长的机会?是什么原因阻碍了非织造布行业的持续发展?无论你们的公司是否是非织造布行业某一分支市场的领导者,只要你是一个事业成功的公司,最好能保持可持续的发展.     

Experimental and theoretical study of the optical and electrical properties of nanostructured indium tin oxide fabricated by oblique-angle deposition

Oblique-angle deposition of indium tin oxide (ITO) is used to fabricate optical thin-film coatings with a porous, columnar nanostructure. Indium tin oxide is a material that is widely used in industrial applications because it is both optically transparent and electrically conductive. The ITO coatings are fabricated, using electron-beam evaporation, with a range of deposition angles between 0 degrees (normal incidence) and 80 degrees. As the deposition angle increases, we find that the porosity of the ITO film increases and the refractive index decreases. We measure the resistivity of the ITO film at each deposition angle, and find that as the porosity increases, the resistivity increases superlinearly. A new theoretical model is presented to describe the relationship between the ITO film's resistivity and its porosity. The model takes into account the columnar structure of the film, and agrees very well with the experimental data.     

A simple analysis of current collection in tubular solid oxide fuel cells

A transmission line analysis is presented for the axial current collection in tubular solid oxide fuel cells (SOFC). Closed form analytical solutions are obtained for two modes of current collection: (1) Current collection at one end. (2) Current collection across opposite ends. The analysis shows that cell resistance is lower for current collection at one end compared to that at the opposite ends, with the best case scenario being current collection at both ends. In addition, the analysis shows that for the case of tubular cells, performance may not indefinitely increase with increasing temperature. Experimental data are presented on planar and tubular cells that demonstrate significant differences in temperature dependence. It is projected that under certain conditions, performance of tubular cells may actually decrease with increasing temperature. A design of tubular cells with spines which can substantially lower current collection losses is described.     

环境烟气颗粒标记物:国际范围的卷烟研究

在室内空气质量的研究中,通常用标记化合物来评估环境烟气(ETS)带来的可呼吸性悬浮颗粒物(RSP).研究测定了ETS-RSP和以下ETS-RSP标记物之间的比率紫外颗粒物(UVPM)、荧光颗粒物(FPM)和茄尼醇,共测定了19个国家和地区的卷烟.在一个不通风的测试间内同时抽吸了每个国家和地区的6个主要牌号的卷烟,实时测定了CO、氮氧化物(NOx)、总碳氢化合物和颗粒物的质量浓度,还对烟碱、3-乙烯基吡啶(3-EP)、RSP、UVPM、FPM和茄尼醇都作了时间加权平均测定.各个国家和地区卷烟的CO、NOx、总碳氢化合物、烟碱、3-EP和颗粒物的浓度都很相似.计算得出ETS-RSP的平均产生量是14.3(12.5～18.7)mg/支.所测定的大多数国家和地区卷烟中标记物与ETS-RSP浓度的比率都是相似的.ETS-RSP与UVPM及FPM替代标准的平均比率分别是7.7和43.茄尼醇约占ETS-RSP重量的2.4%,其约定因子是41.除了少数几个例外,这些平均约定因子可以应用于不同国家或地区室内空气的研究.     

Phosphate Ester Acids as Load-Carrying Additives and Rust Inhibitors for Metalworking Fluids

Alkylaryl- and alkylpolyethylenoxy phosphate ester acids and their salts were found to be effective load-carrying and rust-inhibiting additives for metalworking fluids. Falex and four-ball data showed that performance in oil, emulsion, and water systems were dependent upon the hydrophobe type and ethylene oxide content. Chip tests demonstrated that chemical composition also influenced rust inhibition.     

The structure of intelligence in children and adults with high functioning autism.

Confirmatory factor analyses of the commonly used 11 subtests of the Wechsler child and adult intelligence scales were accomplished for 137 children and 117 adults with high functioning autism (HFA) and for comparable age groups from the standardization samples contained in the Wechsler manuals. The objectives were to determine whether the structure of intelligence in HFA groups was similar to that found in the normative samples, and whether a separate "social context" factor would emerge that was unique to HFA. Four-factor models incorporating a Social Context factor provided the best fit in both the autism and normative samples, but the subtest intercorrelations were generally lower in the autism samples. Findings suggest similar organization of cognitive abilities in HFA, but with the possibility of underconnectivity or reduced communication among brain regions in autism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)